Oh! Keyshawn Johnson has just come out to clear the allegation by Courtney Kardashian, about the Mold in the house sold to her.

Keyshawn Johnson is enraged that Kourtney Kardashian is suggesting he defrauded her by selling her a mold-infested house.

Sources close to Keyshawn tell us he's scoffing at Kourtney's intimation he painted over dangerous black mold so it would go undetected.  In fact ... Keyshawn insists he never painted a single wall during the 2 1/2 years he lived in the Calabasas mansion.

Our sources say ... Keyshawn believes the mold developed AFTER the sale when a bathroom pipe sprung a leak in the wall.  Keyshawn says someone in the Kardashian klan actually reached out to Keyshawn asking if the house was still under warranty so they wouldn't have to pay for the repair.

Keyshawn is incredulous because he has 2 kids who lived in the house until the day before it was sold ... and the kids mostly slept in the master, where mold was found.  He says he would never knowingly expose his kids to mold.

He also says the Kardashians have been a pain in the ass ... calling at least 10 times after the sale to ask about this and that.